Significant advancement in cathode ray tube technology, in particularly the tubes types utilized in television and allied display applications, has produced refinements in the compaction of efficient electron gun structures which are incorporated in tube envelopes having markedly reduced neck diameters. The operating potentials for the various elements of the gun structures are usually supplied via an annular array of connector pins sealed into and projecting from the header or stem closure portion of the tube. As the neck diameters and associated header closure portions become smaller, the spacings between the connector pins decrease in a proportionate manner.
Since many types of tubes evidence large voltage differentials between certain of the connector pins, it is imperative that the base spacings between pins, and the base surface in general, be kept free of deleterious materials to prevent the development of leakage and arcing paths thereacross.
Many base protectors in the prior art did not adequately shield the inter-spacings between pins, and other vunerable areas on the base surface, from foreign materials and liquids that may have inadvertently been deposited thereon. Consequently, the possible shorting-out and the development of leakage or low electrical resistance paths, resultant from the presence of these foreign substances, became important factors in determining the quality of the tube.
Base protectors often incorporate means for maintaining pin alignment, but unless the aforementioned base areas are shielded between the final stages of tube manufacturing, as well as during transportation and storage, the final operational quality of the tube is in jeopardy.